Vertical vacuum diecasting machine



Oct. 5, 1965 G. R. MORTON 3,209,416

VERTICAL VACUUM DIECASTING MACHINE Filed May 2 1962 3 Sheets-Sheet 2 VACL'JUM on. 57

COOLANT VACUUM d- 1965 G. R. MORTON 3,209,416

VERTICAL VACUUM DIECASTING MACHINE Filed May 2, 1962 5 Sheets-Sheet 3 I 771%] ENTOR.

attorneys United States Patent 3,209,416 VERTICAL VACUUM DIECASTING MACHINE Glen R. Morton, 7025 Sarpy Ave., Omaha, Nebr. Filed May 2, 1962, Ser. No. 191,849 9 Claims. (Cl. 22-68) This application is a continuation-in-part of my copending applications, Serial No. 51,903, filed August 25, 1960 for Method of and Means for Producing Dense Articles from Molten Metals, and Serial No. 53,704, filed September 2, 1960, now abandoned, for Fluid Cooled, Lubricated and Sealed Piston Means for Casting Machines.

This invention relates to a vertical diecasting machine, that is, in which the cover half of the die is moved vertically into open and closed relation with a bottom or stationary half of the die and in which the die cavity between those halves is evacuated before and while the cavity is being filled with molten metal to remove the air which otherwise would be trapped therein and to accelerate the movement of the molten metal into the die cavity. By so avoiding contact of the molten metal with air while being drawn into the die cavity, castings can be produced in thinner sections and finer detail; its surface exactly follows the contour of the die cavity and is free from surface imperfections; it is free from occluded air both at the surface and at depth to have improved appearance and freedom from weak spots which are capable of growing with continuing oxidation, and which is denser and of uniform and homogeneous structure throughout.

One of the principal objects of the invention is to provide such a vertical vacuum diecasting machine in which molten metal is transferred rapidly from the bath to the die cavity with a minimum of oxidation, turbulence and possibility of Stratification.

Another object of the invention is to adequately lubricate the shot plunger but at the same time avoid drawing the lubricant into the metal as a result of the vacuum maintained in the shot cylinder. This is achieved by introducing lubricant and also providing a vacuum on the outer end of the shot cylinder when the shot plunger is withdrawn to this outer end, this vacuum balancing the vacuum drawing the molten metal into the inner end of the shot cylinder.

Another object is to avoid drawing of lubricant into the molten metal through the bores for the ejection pins and also the metal shut-0E pin, this being achieved by the provision of a vacuum around these pins, such vacuum also assisting the proper lubrication of the metal shut-off pin.

Another object is to avoid drawing of air into the molten metal through the bores for the ejection pins and metal shut-off pin, this also being achieved by the provision of this vacuum around these pins.

Another object is to provide such a die casting machine which can be operated at high speed, say, in excess of 160 shots per hour with one and one half pounds of aluminum per shot and as high as 380 shots per hour.

To permit of such high speed operation, a secondary object of the invention is to provide adequate cooling of both the shot plunger and the shot cylinder, such cooling being imperative for such high speed operation.

To permit of such high speed operation, another secondary object of the invention is to provide adequate cooling for the die cavity surfaces both from the cover half of the die and also the mating stationary half.

Another object is to provide such a die casting machine which requires minimum floor space.

Another aim is to provide such a die casting machine which is adapted for automation, particularly in the handling of the formed die castings as by the provision of a swinging pallet to remove the same.

3,209,416 Patented Oct. 5, 1965 "ice To this end a secondary object of the invention is to provide straight fall ejection of the die casting from the machine.

Another object is to provide such a die casting machine in which inserts can be placed in the die cavity with greater ease.

Another purpose is to provide such a die casting machine in which the need for excess metal in gates and runners is reduced.

Another object is to protect the dies from the molten metal bath and also to have the metal bath immediately below the dies to minimize transfer of the metal and to conserve floor space.

Other objects and advantages of the invention will be apparent from the following description and drawings in which:

FIG. 1 is a side elevational view, partly in section, of a vertical vacuum diecasting machine embodying the present invention;

FIG. 2 is a fragmentary vertical sectional view taken generally on line 22, FIG. 1;

FIG. 3 is an enlarged fragmentary vertical central section through the central part of the diecasting machine, this view generally following the sections shown in FIG. 1, but illustrating features in greater detail;

FIG. 4 is a fragmentary horizontal section taken on line 4-4, FIG. 3 and illustrating the underside of the horizontal support plate forming the bottom of the ejector box;

FIG. 5 is a horizontal section taken on line 55, FIG. 1 and illustrating the top face of the fixed bottom half of the die;

FIG. 6 is a View on the same line looking upwardly in the direction of the arrows 6-6, FIG. 1, and showing the underside of the cover half of the die;

FIG. 7 is a vertical section through the diecasting as removed from the machine;

FIG. 8 is a top plan view thereof.

The vertical diecasting machine embodying the present invention has a stationary bottom platen 10 with parallel columns 11 fixed to and rising from its rim and which guide a movable platen 12 for vertical movement along these columns toward from the fixed or stationary bottom platen 10. This movable platen is raised and lowered by a main ram 13 which is secured thereto in any suitable manner, and on its underside carries a conventional ejector box or housing indicated generally at 14. This ejector box is shown as having the usual top clamping plate 15 secured to the underside of the movable platen 12 by clamps 16 and bolts 17; vertical side plates or parallels 18 which depend from opposite sides of the top clamping plate 15; a horizontal support plate 19 forming the bottom of the ejector box and secured to the parallels 18 by screws 20 which also secure the cover half of the die as hereinafter described; and a pair of horizontal ejector plates 21 and 22 which are coupled together and are guided for vertical movement in the ejector box. Ejector pins 23 extend through the ejector pin retainer plate 22 and have heads at their upper ends which are held down in engagement with this ejector pin retainer plate by the companion ejector plate 21. A vertical collar 24 is shown as extending vertically through the center of the ejector plate 21 and as having a bottom flange secured between the ejector plates 21 and 22. The head of an upstanding screw 25 is pinned as indicated at 26 or otherwise secured in this collar and screws into a cylindrical head 27 at the lower end of a piston rod 28. This cylindrical head 27 is guided in a vertical bore 29 through the movable platen 12. The cylinder 30 with the piston 31 and the piston rod 28 is mounted in any suitable manner on the moving platen 12 in a cavity 34 in the bottom of the main ram 13. This cylinder 30 is shown as having fluid lines 32 and 33 for actuating the piston 31.

The ejector pins 23 work through vertical bores 35 in the horizontal support plate 19 forming the bottom of the ejector box and work through bores 36 through the cover half 37 of the die, this cover half being secured to the underside of this horizontal support plate 19 by the screws 20 as shown in FIG. 2. As best shown in FIGS. 3 and 6, these ejector pins 23 are adapted to be projected into the cavity 38 in the underside of the cover half 37 of the die. This cavity 38 is shown as being of annular or ring form to produce a diecasting in the form of a collar 39 having an outwardly projecting annular flange 40 at one axial end as shown in FIGS. 7 and 8. The bottom face of this casting is shown as produced by the top face of the bottom or fixed half 41 of the die and which is shown as clamped to the top of the fixed platen 10 by clamps 42 and screws 43. The bottom half 41 of the die has a central vertical through bore 44 in which the upper open end of a shot cylinder 48 is mounted, this shot cylinder having a through bore 49. This shot cylinder also extends through a vertical bore 50 through the fixed platen 10 and has a flange 51 which is clamped between the fixed platen 10 and the fixed or bottom half 41 of the die.

A gate 52 leads from the sprue or top of the bore 44 to the die cavity 38, a gate piece 53 being produced in the diecasting connecting the casting 39 with a biscuit 54 formed in the bore 44 as shown in FIGS. 7 and 8.

The cavity 38 is shown as surrounded by a concentric ring-like passage or vacuum channel 55 formed in the bottom of the cover half 37 of the die. At One side, this passage or channel 55 is connected with the die cavity 38 by a vacuum groove 56 which is closed by a vertical vac- -uum groove shut-off pin 57 which when lowered completely shuts 011 this vacuum groove 56 from the vacuum channel 55. The metal 58 drawn into this vacuum groove 56 is cut off by this vacuum groove shut-01f pin 57.

This vacuum groove shut-ofl pin 57 works in a vertical bushing 59 through the cover half 37 of the die and in a bore 60 in the horizontal support plate 19 forming the bottom of the ejector box 14. This pin 57 also extends up through a through bore in the ejector pin retainer plate 22 and has a head 61 clamped between the ejector plates 21 and 22. With this vacuum groove shut-off pin 57 raised, the die cavity 38, gate 52 and bore 49 of the shot cylinder 48 are evacuated via the ring-like vacuum passage 55 and its outlet 63 which is arranged on the opposite side of the die from the vacuum groove shut-off pin -7 and connects with a vacuum pipe 64 leading to a metal trap 65, this in turn being connected by a vacuum conduit 66, having a shut-off valve 68, with the vacuum line 69 of the plant. The metal trap 65 is designed to prevent metal particles from entering the vacuum line 69 and is preferably constructed asshown in my Patent No. 2,958,105, dated November 1, 1960 for Flowable Material Separator for the Vacuum System of Vacuum Casting Equipment.

A feature of the invention also resides in evacuation of the slideways for both the ejector pins 23 and the vacuum groove shut-01f pin 57, the primary purpose of such evacuation being to prevent air from jetting into the molten metal around these pins. A secondary purpose of such evacuation is to draw lubricant around the vacuum groove shut-off pin 57. To this end a branch 70 of the vacuum conduit 66 connects with a passage 71 in the cover half 37 of the die, this passage leading to the under face of the horizontal support plate 19. This under face is shown as provided with an annular groove 72 which embraces the group of ejector pins 23. This annular groove, of course, prevents air from leaking between the bottom face of the horizontal support plate 19 and the top face of the cover half 37 of the die to the slideways 35 for the ejector pins 23 and it has also been found that leakage is also prevented downwardly through the slideways 36.

The bushing 59 for the vacuum groove shut-off pin 57 is directly evacuated by a passage 73 in the cover half 37 of the die leading to an opening 74 through the bushing. Lubricant is drawn from an oil cup 75 which connects with another passage 76 leading through an opening 78 to the bore of the bushing 59. Here again the jetting of atmospheric air into the molten metal is prevented.

The shot cylinder 48 contains a shot plunger 81 which is shown as having a hollow beryllium-copper cylindrical head 82 and a stem or rod 83, the latter having inlet and outlet coolant passages 84, 85 conducting a coolant from inlet and outlet lines 86, 88 to the chamber 89 in the hollow head 82. The lower extremity of the shot plunger rod 83 is connected by a coupling 90 with the upper end of a piston rod 91 of a piston 92 in a vertical cylinder 93. The piston 92, is actuated by fluid alternately introduced into and relieved from lines 94 and 95 at opposite ends of the piston 93. The exterior face 96 of the coupling provides a cam face actuating a normally closed electric switch 98.

A feature of the invention resides in the lubrication of the shot plunger head 82 to facilitate its proper operation under repeated service. To this end an annular groove 100 is provided inside the bore 49 of the shot cylinder 48 near the bottom thereof. This annular groove is connected by a passage 101 with an oil cup 102. Immediately below the annular groove 100 a second annular groove 103 is provided in the bottom of the shot cylinder bore 49. This groove 10-3 connects with a vacuum line 104 having a metal trap or separator 105 and a remote control valve 106 which opens when the shot plunger 81 reaches its bottom position. With the shot plunger 81 in its bottom position, it will be seen that the application of vacuum to the groove 103 draws lubricant from the groove 100 along the periphery of the shot plunger head 82 to lubricate the same preparatory to its next stroke.

The bath 110 of molten diecasting metal is shown as contained in a commercial furnace 111 with a slant front 112 and having a thermal insulation liner 113. The metal from the bath 110 is withdrawn by a metal feed tube 115 which preferably is made in the manner described in my copending application, Serial No. 88,873, filed February 13, 1961 for Molten Metal Feeding Tube for Metal Casting Machines. As shown in simplified form herein, the feed tube 115 discharges into a side opening 116 in the bottom of the shot cylinder 48 and comprises a metal outer tube 118 having its lower end immersed in the bath 110 and having a thermal insulation liner 119 providing a passageway 120 of diminishing cross section from its lower immersed end to a chamber 121 at its upper end and into which the molten metal can advantageously be introduced centrifugally as described in greater detail in my said copending application. A thermal insulating ring 122 is interposed between the upper end of the hot metal tube 118 and the shot cylinder 48, which is fluid cooled as hereinafter described, and the metal passes through the opening in this insulation ring into the bore 49 of the shot cylinder. A clamping screw 125 working from a nut 126 fixed to a bracket 128 and working against a seat 129 on the upper end of the metal tube 118 serves to clamp the feeding tube 118 in place.-

Features of the invention reside in fluid cooling both the upper end and middle part of the shot cylinder 48. as well as the cover half 37 and fixed half 41 of the: die. To this end a groove 130 of substantial height is. provided in the bore 44 in the bottom or fixed half 41 of the die, this groove thereby surrounding the shot cylinder 48 and also surrounding the head 82 of the shot plunger when it is in its fully upwardly projecting position. This groove can be supplied with coolant through inlet and outlet passages 131, 132 which connect respectively with coolant supply and return lines 133 and 134. Similarly, a groove 135 of substantial vertical extent is provided around that part of the shot cylinder 48 which is embraced by the fixed platen 10 of the die. This groove is supplied with coolant through passages 136, 138 which connect respectively with coolant inlet and outlet lines 139 and 140. At its center, above the die cavity 38, the cover half 37 of the die is provided with a depression 141 which is of substantial horizontal area. This depression is provided with coolant from a passage 142 connecting with a coolant supply line 143 and the coolant is discharge through a passage 144 to a coolant return line 145.

Operation In this description of the operation of the vertical diecasting machine, it is assumed that the bath 110 of molten diecasting metal is being maintained in the slant front furnace 111; that suction or vacuum of adequate value is constantly available in the plant vacuum line 69 as well as the line 104; that the oil cups 75 and 102 are operative; that coolant is supplied from the lines 133, 139 and 143; and that fluid pressure for operation of the main ram 13, which is assumed to be raised, and the shot plunger 81, which is assumed to be down, and the piston 31 in cylinder 30, which is assumed to be up. The operation of the shot plunger 81 in conjunction with the metal cutoff pin 57 is described in greater detail in my copending application Serial No. 694,315, filed November 4, 1957 for Vacuum Casting Machine, now Patent No. 3,121,926 to which reference is made for a more detailed description of this phase of the operation. In general, the operator admits fluid to the main cylinder (not shown) to lower the main ram 13 and close the cover half 37 of the die against the bottom fixed half 41 of the die. After the dies have contacted, full pressure is admitted against the main ram 13 to clamp the dies together under the full predetermined pressure and the remote control vacuum valve 68 is opened to evacuate the die cavity 38 (via lines 66 and 64, passage 63, annular vacuum groove 55 and vacuum passage 56); the bore 49 of the shot cylinder 48 (from this die cavity 38 via the gate 52 and top of bore 44 in the bottom or fixed half of the die); the annular vacuum groove 72 (via line 70 and passage 71); and the bore in the bushing 59 for the metal shutoff pin 57 (from this annular vacuum groove 72 via passage 73 and opening 74).

This evacuation of the die cavity 38, by the elimination of air which otherwise would be trapped therein, and by the acceleration of the movement of the molten metal into the die cavity and by avoiding contact of this molten metal with air while being drawn into the die cavity, results in a casting which can be produced in very thin sections and very fine detail which otherwise could not be achieved; which has a uniform surface exactly following the contour of the dies and is free from depressions, pitting or other surface imperfections; which is free from occlusions of air both in the surface and at depth, thereby to have improved surface appearance free from subsequent subsurface oxidation and well as to be free from deeper weak spots and defects as Well as such weak spots and defects which will grow as a result of continued oxidation; and which is denser and of uniform structure throughout.

The above evacuation of the bore 49 of the shot cylinder 48 serves to draw the molten metal from the bath 110 up the passage 120 and chamber 121 of the feed tube 115 into the bore 49 of the shot cylinder. This movement is the result of atmospheric pressure on the surface of the bath 110 and it will be observed that by reason of the vertical position of the shot cylinder 48 there is minimum oxidation of the metal entering the shot cylinder, this being not only due to its exposure to the rarefied atmosphere of the vacuum and minimizing entry turbulence but also to the fact that there is minimum surface contact between the rising molten metal in the shot cylinder and the superposed rarefied atmosphere due to the fact that cross sectional area of the bore of the shot cylinder is minimum in a horizontal direction.

The above evacuation of the annular vacuum groove 72 serves to intercept air leaking between the bottom 6 7 face of the support plate 19 and the top face of the cover half 37 of the die from the margins of these parts. This prevents such leaking air from being drawn down the bores 36 for the ejector pins and being jetted or orificed into the die cavity 38. As is well known in the vacuum diecasting art, such leaks in the ejector pin bore 36 are detrimental as such leaks will jet or orifice air into the molten metal in the die cavity until the pressure of the molten metal has exceeded atmospheric pressure. Even with complete evacuation of the die cavity 38, if such leaks in the ejector pin bores 36 exist, it is possible to have more air in the casting than if the die cavity werent evacuated in the first place.

Since the tolerance of the ejector pin bores 35 in the support plate 19 can be maintained closer than between the opposing faces of this support plate 19 and the cover half 37 of the die, it will be seen that the vacuum in the annular groove 72 will also serve to capture any air leaking down these bores 35 and prevent such air from entering the bores 36 and jetting into the molten metal as described immediately above.

The above evacuation of the bore of the bushing 59 for the metal shut-off pin 57 has two results. First it traps any air leaking down this bore and prevents such air from being jetted into the molten metal as just described with reference to trapping air which would otherwise leak down the ejector pin bores 36. Secondly this vacuum in the bore of the bushing 59 draws oil into this bore to insure the rapid and sure operation of the metal shut-off pin 57. This oil is supplied from the oil cup 75 to this bore via the passage 76 and opening 78.

The above evacuation of the shot cylinder bore 49 is timed to fill this bore with a shot of only that amount of molten metal required to produce a desired casting and with a minimum size biscuit 54 as waste. This fill is determined by timing the action of the shot plunger 31 in relation to opening the vacuum valve 68, this action of the slot plunger 81 being eifected by introducing fluid through the line into the bottom of the cylinder 93 to project the piston 92 and its rod 91 upwardly. Through the coupling 90 this raises the plunger 81, its head 82 travelling up the bore 49 of the shot cylinder 48 to raise the column of molten metal now contained in this bore.

When the shot plunger 'head 82 passes the metal inlet opening 116 in the side of the shot cylinder 48 return of molten metal to the feed tube and bath 1111 is cut off and this column is projected to flow first through the gate 52 into the die cavity 38 and around and incompletely filling this evacuated die cavity. Following this the molten metal reaches the outlet passage 56 from the die cavity but emergence of the molten metal from this passage 56 is prevented by downward movement of the metal shutoff pin 57 which closes the exit of this passage 56 into the vacuum groove 55. If through missetting or malfunctioning this shut-off pin 57 did not cut off the flow of metal from the die cavity exactly in time, such metal would merely flow into the annular vacuum groove 55 and be removed as waste along with the casting 39. This downward movement of the metal shut-off pin is effected by the cam face 96 of the coupling 90 for the stem 83 of the shot plunger 81 closing the electrical switch 98, this in turn introducing fluid under pressure in the top of the cylinder 30 to drive its piston 31 downwardly. This, through the piston rod 28, coupling 27, screw 25, collar 24 and connected ejector plates 21 and 22 drives the metal shut-01f pin 57 downwardly until it seats against the bottom or fixed die half 41 to close the outlet passage 56 from the die cavity 38.

This also brings the bottoms of the ejector pins 23 to the top face of the cavity 38.

After such closing of the metal shut-01f pin 57, the shot plunger 81 continues in its upward movement in the shot cylinder 48 and still more molten metal is displaced by the shot plunger 81 into the die cavity 38 completely filling the mold cavity, including very thin sections thereof which could not be molded without such combination of vacuum and shot plunger pressure in the mold cavity. All gates and runners are filled and any excess metal is formed into the biscuit 54, at the top of the bore 44, it being desirable, however, to reduce the amount of metal in these excess parts of the casting to a minimum.

After a predetermined lapse of time, the vacuum valve 68 is closed and at the same time fluid pressure is applied to raise the main ram 13. This raises moving platen 12, the ejector box 14 clamped to the underside of this platen, and the cover half 37 of the die secured to the bottom of this ejector box to separate the die halves. This upward movement of the cover half 37 of the die is followed by continued upward movement of the shot plunger 81, which, bearing against the underside of the biscuit 54 prevents the casting 39 falling from the die cavity 38 in the rising cover half 37 of the die.

At a predetermined point in the rising movement of the cover half 37 of the die, the upward movement of the shot plunger 81 is stopped and fluid under pressure is introduced into the top of the cylinder 30 to further depress the piston 31, piston rod 28, coupling 27, screw 25, collar 24, ejector pin plates 21 and 22 and ejector pins 23. The downward movement of the latter pushes the casting 39 downwardly out of the die cavity 38 to be removed by the operator who then cleans and lubricates the dies.

The cycle is completed by retraction upwardly of the ejector pins 23 and the metal shut-off pin 57 by raising the ejector pin retainer plates 21 and 22 through introduction of fluid pressure into the bottom of the cylinder 30 and by retracting the shot plunger 81 downwardly through introduction of pressure into the top of the cylinder 93.

When the shot plunger 81 reaches the bottom of its stroke it is encompassed by the oil groove 100 and vacuum groove 103 and the valve 106 is opened to evacuate the vacuum groove 103. This draws oil from the oil groove 100, supplied from the oil cup 102, along the periphery of the shot piston head 82 to lubricate the same.

It will be noted that this shot piston head is constantly internally cooled by coolant supplied by the lines 86, 88. It will also be noted that the shot cylinder 48 is cooled at its upper end by the jacket groove 130* in the lower stationary half 41 of the die which is supplied with coolant from the lines 133 and 134, this jacket groove also serving to cool the fixed or bottom half 41 of the die at the die cavity region thereof. It will also be noted that the shot cylinder 48 is cooled at its center by the jacket groove 50 in the bottom or stationary platen which is supplied with coolant from the lines 139, 140. It will also be noted that the cover half 37 of the die is cooled in the region of its die cavity 38 by the jacket chamber 141 in this cover half 37 which is supplied with coolant from the lines 144, 145.

From the foregoing, it will be seen that with a vertical vacuum diecasting machine having the arrangement of the parts as described, a very short, almost straight line movement of the molten metal from the bath 110 to the die cavity 38 is achieved in minimum time and with minimum turbulence and oxidation of the molten metal.

Thus it will be observed that by the provision of the shot cylinder 48 in the bores 44 and 50 of the lower die half 41 and bottom stationary platen 10, respectively, with its upper end in communication, via the gate 52, with the mold cavity 38, and with the molten metal bath 110 arranged beneath and having a part 112 extending close to the shot cylinder 48 and connected therewith by the shot tube 115, portions of the molten metal bath 110, feeding tube 115, and bore 49 of the shot cylinder are in a straight line with each other and also in rectilinear relation with the cavity area 38 of the die halves so that there is a short and direct movement of the metal up the and up this bore through the gate 52 into the mold cavity 38 (under the influence of the shot plunger 82). Not only is this travel minimized by such short and direct generally rectilinear movement, but turbulence is reduced in the discharge of molten metal from the opening 121 into the side of a vertical bore 49 as compared with the sloshing around that would follow from discharge into a horizontal shot cylinder bore. Further the only oxidizing influence is the rarefied atmosphere above the molten metal in the shot cylinder 48 and since the minimum area of the bore 49 is in a horizontal direction, it will be seen that there is much less contact with this rarefied atmosphere than if the shot cylinder 48 were horizontally disposed.

It will also be seen that with this arrangement the shot cylinder 48 is held in position by the simple provision of its outwardly projecting horizontal flange 51 between the stationary bottom platen 10 and the lower die half 41.

This arrangement also lends to adequate cooling of the shot cylinder 48 for rapid cycling, the bottom platen 10 being provided with the horizontal annular groove 50 embracing the shot cylinder'and supplied with coolant from the lines 139, 140 and the lower die "half 41 having its bore 44 similarly provided with the horizontal annular groove 130 embracing the shot cylinder 48 and supplied with coolant from the lines 133, 134.

This arrangement also permits of preventing air being drawn in around the retracted shot plunger head 82 to enter the molten metal being drawn into the shot cylinder above this plunger head. Thus, in the retracted position of this shot plunger head 82 it is embraced by the groove 103 which is being evacuated via the vacuum line 104 to balance the vacuum at opposite ends of the shot plunger head 82 and in any event to insure that air leaking in around the bottom of this shot plunger head 82 is withdrawn via the vacuum line 104 and does not enter the molten metal above this shot plunger head. Also by the provision of the horizontal annular groove around this retracted shot plunger head 82 immediately above the evacuated groove 103, adequate lubrication of the shot plunger head 82 is assured.

It will also be seen that by the provision of the chamber 141 on top of the cover die half 37, and supplying coolant to this chamber via the lines 143 and 145, additional cooling of the area around the die cavity 38 is provided to permit of more rapid cycling of the machine.

An important feature of the invention is the evacuation of the upper ends of the bores 36 in the cover half 37 of the die for the ejector pins 23 via the vacuum groove 72 embracing the upper ends of these bores in closely spaced relation thereto. This evacuation guards against air being drawn into the die cavity 38 through these bores either via the interface clearance between the cover half 37 of the die and the support plate 19 to which it is attached, or through the bores 35 in this support plate of the ejector pin box.

Equally important is the evacuation of the bore of the bushing 59 for the metal shut-off pin 57, this being achieved through the vacuum passage 73 and opening 74. This prevents atmospheric air from leaking down the bore for this metal shut-off pin 57 into the molten metal in the die cavity 38. Further by the provision of the lubricant duct '76 and opening 78 this evacuation of the bore for the metal shut-off pin 57 is utilized to provide adequate lubrication for this important pin.

It will therefore be seen that the invention achieves the objectives and has the many advantages first enumerated.

I claim:

1. In a vertical diecasting machine, a stationary bottom platen, a lower die half fixed to the upper face of said stationary bottom platen, an upper movable platen arranged over and movable vertically relative to said stationary lower platen and die half, a cover die half fixed to the under face of said upper movable platen and mating with the upper face of said lower die half, said die halves defining between them a mold cavity, a shot cylinder communicating with said mold cavity, a molten metal bath below said bottom platen, a feeding tube between the bore of said shot cylinder and said molten metal bath, a shot plunger in said bore of said shot cylinder and retractable to establish communication between said bore of said shot cylinder and said feeding tube, means evacuating said mold cavity when said cover and lower dies are in mating contact, and means for actuating said shot plunger to progressively draw a charge of molten metal into said shot cylinder and to project said charge of molten metal from said shot cylinder into said evacuated die cavity, vertical ejector pin bores through said cover die half and terminating at their lower ends in said mold cavity, ejector pins in said ejector pin bores, means moving said ejector pins in said bores and into and out of said mold cavity, and means evacuating the upper ends of said ejector pin bores.

2. In a vertical vacuum diecasting machine, the combination set forth in claim 1 wherein said means evacuating the upper ends of said ejector pin bores comprises a groove the bottom of which is formed by the upper face of said cover die half and which groove is arranged close to each of said ejector pin bores, and means evacuating said groove.

3. In a vertical diecasting machine, a stationary bottom platen, a lower die half fixed to the upper face of said stationary bottom platen, an upper movable platen arranged over and movable vertically relative to said stationary lower platen and die half, a cover die half fixed to the under face of said upper movable platen and mating with the upper face of said lower die half, said die halves defining between them a mold cavity, a shot cylinder communicating with said mold cavity, a molten metal bath below said bottom platen, a feeding tube between the bore of said shot cylinder and said molten metal bath, a shot plunger in said bore of said shot cylinder and retractable to establish communication between said bore of said shot cylinder and said feeding tube, means evacuating said mold cavity when said cover and lower dies are in mating contact, and means for actuating said shot plunger to progressively draw a charge of molten metal into said shot cylinder and to project said charge of molten metal from said shot cylinder into said evacuated die cavity, vertical ejector pin bores through said cover die half and terminating at their lower ends in said mold cavity, ejector pins in said ejector pin bores, means moving said ejector pins in said bores and into and out of said mold cavity, and means evacuating the upper ends of said ejector pin bores, said means evacuating the upper ends of said ejector pin bores comprises an annular groove disposed outwardly of the ejection pin bores, the bottom of which is formed by the upper face of said cover die half and which groove is arranged close to each of said ejector pin bores, and a plate is matingly secured to the upper face of said cover die and forms one wall of said groove, and means for evacuating said groove.

4. In a diecasting machine, a stationary platen, a die half fixed to the one face of said stationary platen, a movable platen movable relative to said stationary platen and die half, a die half fixed to one face of said movable platen and mating with the adjacent face of said stationary platen die half, said die halves defining between them a mold cavity, a shot cylinder communicating with said mold cavity, a molten metal bath adjacent said stationary platen, a feeding tube between the bore of said shot cylinder and said molten metal bath, a shot plunger in said bore of said shot cylinder and retractable to establish communication between said bore of said shot cylinder and said feeding tube, an annular groove disposed outwardly of said cavity and formed between said die halves, an evacuation duct extending between said die halves from said mold cavity, and terminating at said annular groove, a vacuum means in communication with said annular groove for said evacuation duct to evacuate said mold cavity and shot cylinder to draw a charge of molten metal into said cylinder, means actuating said shot plunger to project said charge of molten metal into said mold cavity, a metal shut-off pin bore in one of said die halves and terminating in said evacuation duct, a metal shutoff pin in said metal shut-01f bore and movable to close said evacuation duct and cut off the flow of molten metal therethrough, and means evacuating said metal shut-off pin bore.

5. In a vacuum diecasting machine, the combination set forth in claim 4 additionally including means for supplying lubricant to said metal shut-01f pin bore, said means evacuating said metal shut-off pin bore being adapted to draw oil from said lubricant supplying means for application to said shut-off pin and said shut-01f pin bore.

6. In a diecasting machine, a stationary platen, a die half fixed to the one face of said stationary platen, a movable platen movable relative to said stationary platen and die half, a die half fixed to one face of said movable platen and mating with the adjacent face of said stationary die half, said die halves defining between them a mold cavity, a shot cylinder communicating with said mold cavity, a molten metal bath adjacent said stationary platen, a feeding tube between the bore of said shot cylinder and said molten metal bath, a shot plunger in said bore of said shot cylinder and retractable to establish communication between said bore of said shot cylinder and said feeding tube; means for evacuating said mold cavity when said dies are in mating contact, and for actuating said shot plunger to progressively draw a charge of molten metal into said shot cylinder and to project said charge of molten metal from said shot cylinder into said evacuated die cavity, ejector pin bores through said movable die half and terminating in said mold cavity, ejector pins in said ejector pin bores, means moving said ejector pins in said bores and into and out of said mold cavity, and means evacuating the outer ends of said ejector pin bores, said means evacuating the outer ends of said ejector pin bores comprises an annular groove disposed outwardly of the ejector pin bores in a plane perpendicular to the longitudinal axis of said ejector pin bores.

7. In a diecasting machine, the combination set forth in claim 6 wherein the bottom of said annular groove is formed by the outer face of said movable die half and which groove is arranged close to each of said ejector pin bores, and a plate is matingly secured to the outer face of said movable die and forms one wall of said groove, and means for evacuating said groove.

8. In a diecasting machine, a stationary platen, a die half fixed to the one face of said stationary platen, a movable platen movable relative to said stationary platen and die half, a die half fixed to one face of said movable platen and mating with the adjacent face of said stationary die half, said die halves defining between them a mold cavity, a shot cylinder communicating with said mold cavity, a molten metal bath adjacent said stationary platen, a feeding tube between the bore of said shot cylinder and said molten metal bath, a shot plunger in said bore of said shot cylinder and retractable to establish communication between said bore of said shot cylinder and said feeding tube, an annular groove disposed outwardly of said cavity and formed between said stationary and movable dies, an evacuation duct leading from said mold cavity and terminating at said annular groove, vacuum means in communication with said annular groove for evacuating said evacuation duct to evacuate said mold cavity, when said dies are closed, and shot cylinder to draw a charge of molten metal into said cylinder and actuate said shot plunger to project said charge of molten metal into said mold cavity, a metal shut-off pin bore in said movable die half and terminating in said evacuation duct, a metal shut-0E pin in said metal shut-01f bore and movable to close said evacuation duct and cut off the flow of molten metal therethrough, at least one ejector pin bore through said movable die half and terminating at one end in said mold cavity, an ejector pin in said ejector pin bore, means for moving said ejector pin in said bore and into and out of said mold cavity, and means for evacuating the outer end of said ejector pin and shut-off pin bores, said last mentioned means comprising an annular groove formed in said movable die half outwardly from said stationary die and said first mentioned annular groove and adjacently outwardly of said ejector pin, and a passageway extending from said second mentioned groove to the metal shut-off bore.

9. In a diecasting machine, the combination set forth in claim 8 wherein the end opposite said die cavity of said bore in said shot cylinder provides one wall of an annular groove embracing siad shot plunger in the retracted position of the latter, and means evacuating said groove, and said bore in said shot cylinder provides one wall of a second annular groove immediately adjacent said first annular groove and also embracing said shot plunger in the retracted position of the latter, said plunger 12 having a wall serving as another wall of said first and second grooves and means supplying lubricant to said second groove whereby said means for evacuating said grooves serves to draw oil into said second groove from said lubricant supply means.

References Cited by the Examiner UNITED STATES PATENTS MARCUS U. LYONS, Primary Examiner.

20 MICHAEL V. BRINDISI, Examiner. 

1. IN A VERTICAL DIECASTING MACHINE, A STATIONARY BOTTOM PLATEN, A LOWER DIE HALF FIXED TO THE UPPER FACE OF SAID STATIONARY BOTTOM PLATEN, AN UPPER MOVABLE PLATEN ARRANGED OVER AND MOVABLE VERTICALLY RELATIVE TO SAID STATIONARY LOWER PLATEN AND DIE HALF, A COVER DIE HALF FIXED TO THE UNDER FACE OF SAID UPPER MOVABLE PLATEN AND MATTO THE UNDER FCE OF SAID UPPER MOVABLE PLATEN AND MATHALVES DEFINING BETWEEN THEM AND MOLD CAVITY, A SHOT CYLINDER COMMUNICATING WITH SAID MOLD CAVITY, A MOLTEN METAL BATH BELOW SAID BOTTOM PLATEN, A FEEDING TUBE BETWEEN THE BORE OF SAID SHOT CYLINDER AND SAID MOLTEN METAL BATH, A SHOT PLUNGER IN SAID BORE OF SAID SHOT CYLINDER AND RETRACTABLE TO ESTABLISH COMMUNICATION BETWEEN SAID BORE OF SAID SHOT CYLINDER AND SAID FEEDING TUBE, MEANS EVACUTAING SAID MOLD CAVITY WHEN SAID COVER AND LOWER DIES ARE IN MATING CONTACT, AND MEANS FOR ACTUATING SAID SHOT PLUNGER TO PROGRESSIVELY DRAW A CHARGE OF MOLTEN METAL INTO SAID SHOT CYLINDER AND TO PROJECT SAID CHARGE OF MOLTEN METAL FROM SAID SHOT CYLINDER INTO SAID EVACUATED DIE CAVITY, VERTICAL EJECTOR PIN BORES THROUGH SAID COVER DIE HALF AND TERMINATING AT THEIR LOWER ENDS IN SAID MOLD CAVITY, EJECTOR PINS IN SAID EJECTOR PIN BORES, MEANS MOVING SAID EJECTOR PINS IN SAID BORES AND INTO AND OUT OF SAID MOLD CAVITY AND MEANS EVACUATING THE UPPER ENDS OF SAID EJECTOR PIN BORE. 